Disinfection generally involves the use of a chemical agent and/or procedure to inhibit the activity of, and preferably, substantially eliminate virtually all recognized pathogenic microorganisms. Most disinfectants do not necessarily eliminate all microbial forms (e.g., bacterial endospores), and many have toxic side effects. In general, three levels of disinfection are recognized: high, intermediate, and low. High-level disinfection eliminates all organisms, with the exception of high levels of bacterial spores. Intermediate-level disinfection eliminates mycobacteria, most viruses, and bacteria. Low-level disinfection eliminates some viruses and bacteria.
Disinfectants can be quite expensive and are costly for long term, frequent applications. Also, since many disinfectants are rapidly inactivated by organic matter, objects that are to be disinfected usually need to be cleaned thoroughly with warm water and detergent prior to disinfection, which can be time-consuming. In addition, some disinfectants are toxic and therefore are potentially dangerous and hazardous to humans.
Sterilization involves the use of a physical or chemical procedure to substantially destroy all forms of microorganisms (cells, pathogens, viruses, bacteria, fingi, spores, and molds), including highly resistant bacterial endospores. Common sterilizing systems and methods include the use of moist heat by steam autoclaving, ethylene oxide gas, dry heat, and chemical vapor.
Steam autoclaving has the advantages of providing relatively rapid turnaround time, low cost per cycle, and it does not require the use of toxic chemicals. However, due to moisture and generally high temperature operation, steam autoclaving may degrade instruments and cannot be used with many plastics. Steam autoclaving also requires the use of distilled, deionized water, which is difficult to generate and can become expensive. Other disadvantages of steam autoclaving include: the high-cost of an autoclave unit, the need for a relatively large area of space to place the autoclave, and the need for constant maintenance.
Sterilization using ethylene oxide gas (ETO) requires relatively low temperatures and can be quite effective to inactivate or kill microbial cells. ETO's small molecular size also allows penetration into minute openings and porous substances, allowing sterilant into areas that may not normally receive exposure from other methods of sterilization. However, ETO vaporizes at room temperature and is therefore difficult to contain. It is also extremely explosive unless mixed with other gases. In addition to the problems stemming from ETO's molecular structure, its molecular activity can enable it to combine with many other materials (and/or chemicals) to form new compounds. One hazard of employing ETO is that during sterilization it can easily penetrate thin layers of most plastics and virtually all medical devices. Further, an ETO sterilization cycle can take up to two to three hours and a lengthy aeration time must follow each cycle.
Sterilization by dry heat is generally conducted in an oven equipped with forced air circulation. The heat destroys microorganisms by causing irreversible damage to the cellular components. A typical sterilization process with dry heat is performed at high temperatures (e.g. 160° C. for 2 hours). The challenge in dry heat sterilization is to obtain and maintain an even, high temperature distribution among the goods being sterilized. Furthermore, dry heat sterilization is a very time-consuming process and cannot be used with plastics.
Chemical vapor sterilization generally does not cause corrosion and rusting, and objects sterilized using chemical vapor are dry at the end of the sterilization cycle. However, chemical vapor sterilization generally uses toxic chemicals, which require specialized and vigorous handling and ventilation requirements.
Various water treatment technologies are known and used in the art. U.S. Pat. No. 5,591,317 discloses an electrostatic-field generator for use in water treatment that consists of a vitrified ceramic tube of unibody construction having a single open end adapted to receive a high-voltage power cable through an insulated cap. The interior surface of the ceramic tube is lined with a layer of conductive material electrically connected to the power cable, thereby providing a relatively-large conductive surface in intimate contact with the dielectric surface of the ceramic tube. In operation, the device is immersed in a body of water connected to ground and the power cable is energized with a high DC voltage, thereby creating an electrostatic field across the dielectric of the tube's ceramic and across the body of water. Because of the difference in the dielectric coefficients of the materials, the majority of the applied potential is measured across the water, thus providing the desired electrostatic effect on its particulate components.
U.S. Pat. No. 5,817,224 discloses a method for enhancing the efficiency of a solid-liquid separation process by using an electrostatic-field generator that utilizes a vitrified ceramic tube of unibody construction having a single open end adapted to receive a high-voltage power cable through an insulated cap. The interior surface of the ceramic tube is lined with a layer of conductive material electrically connected to the power cable, thereby providing a relatively-large conductive surface in intimate contact with the dielectric surface of the ceramic tube. The device is used in connection with conventional chemical additives for separating suspended solids from water to reduce chemical consumption and improve operating efficiency. The device is immersed in the water carrying suspended particles upstream of the treatment with chemical agents and is energized with a high DC voltage, thereby creating an electrostatic field across the dielectric of the tube's ceramic and across the body of water. The charge on the surface of particles to be separated by physical aggregation is altered by the electrostatic field so generated and is manipulated so as to produce enhanced performance by the chemicals used in the conventional process downstream.
U.S. Pat. No. 4,772,369 discloses a process and an apparatus for treating water which comprises decomposing the minerals dissolved in the water into cations comprising ferromagnetic, paramagnetic and residual particles, and disaggregating the cations and anions by utilizing ferromagnetic particles as a temporary mobile anode facing a strong cathode and paramagnetic particles as a weak cathode. The disaggregated minerals form a dielectric layer on the strong cathode, which is extracted.
U.S. Pat. No. 6,679,988 discloses a water purification system for production of USP purified water and/or USP water for injection including a backwashable, chlorine tolerant microfilter or ultrafilter for initial filtration of the feed water. The filtrate from the filter is provided to a dechlorinator prior to being subjected to an optional, reverse osmosis membrane unit and then to a still which discharges purified water at USP standards for purified water or water for injection.
U.S. Pat. No. 6,689,270 discloses a water treatment apparatus reducing hard water deposits in a conduit. Water having dissolved salts therein causing scaling is treated by flowing through a passage in an elongate tubular member. The tubular member has a first metal inside surface exposed to the water. A second metal surface is positioned therein and the two surfaces have areas of 1:1 up to about 125% with the second metal being different from the first metal. The metal surfaces are electrically insulated from each other so that current flow between the two is through the water.
U.S. Pat. No. 6,849,178 discloses an apparatus for water treatment by means of an electrical field is provided with an anode and a cathode in at least one treatment chamber through which the water to be treated passes. The apparatus is characterized in that the at least one treatment chamber forms a prismatic space with an elongated cross section, the anode and the cathode are formed by pairs of parallel, stick-shaped electrodes which extend spaced apart into said space and a voltage is applicable between the electrodes. One end of the at least one treatment chamber is connected to a water inlet and the other end of the at least one treatment chamber is connected to a water outlet, whereby a waterflow from one electrode to the other is generated, which is substantially transverse to the longitudinal axes of the electrodes.